Schneider Electric 9999-SX-8 Electrical Interlock

Schneider Electric's 9999-SX-8 is an external, field-convertible auxiliary contact kit for Type S NEMA motor starters and contactors, delivering a 1 normally open / 1 normally closed (NO/NC) isolated contact pair in a single accessory. Mounted on the starter assembly externally, the 9999SX8 enables interlocked control and signaling without occupying the main coil, and it can be wired for use with either signaling or interlock logic in motor-control panels. The accessory is designed for NEMA Type S starters in sizes 00 through 7, supports up to 600 V, and is configurable in the field to match the desired circuit arrangement. As part of the Square D 9999 family, it provides a compact, replaceable option for expanding the control logic of a Type S starter when an extra NO/NC contact is required. Typical applications include interlocking between multiple starters, motor-control circuits requiring a dedicated signaling contact, and any panel where an external 1 NO/1 NC contact block is needed to monitor or actuate auxiliary functions. Schneider Electric lists 9999SX8 as a stock item in many distributions, confirming availability for replacement or new installations.